1. Field of the Invention
The invention relates to methods and devices to clear obstructive debris from medical tubes. More particularly, it relates to such a device having a clearance member that can be actuated to draw such debris proximally in a medical tube without compromising the sterile field.
2. Description of Related Art
Millions of medical tubes are used every year to drain bodily fluids and secretions from within body orifices. For example, such tubes can be used to drain fluid from one's bladder, from the colon or other portions of the alimentary tract, or from the lungs or other organs in conjunction with various therapies. Medical tubes also are used to drain blood and other fluids that typically accumulate within the body cavity following traumatic surgery. In all these cases, a tube is inserted into the patient so that its terminal end is provided in or adjacent the space where it is desired to remove accumulated or pooled fluid, and the proximal end remains outside the patient's body, where it is typically connected to a suction source.
One of the biggest categories of patients requiring medical tube drainage is patients who have had heart and lung surgery, nearly all of whom require at least one chest tube to drain the space around the heart and lungs after surgery. Chest tubes are long, usually semi-stiff, plastic tubes that are inserted into the chest in the vicinity of the heart and lungs to drain collections of fluids or air from within the pleura, the mediastinum or pericardial space, or from within the thoracic cavity generally.
In all cases, fluid and other material accumulating in the vicinity of the medical tube's distal end (within the patient) is drawn through that tube and out of the space where it accumulated via suction applied at the tube's proximal end. Ideally, the medical tube will remain free from clots and other debris that may partially or totally obstruct the suction pathway within the medical tube. Unfortunately, however, bodily secretions (particularly those including blood or blood platelets) often form clots within medical tubes, which can partially or totally obstruct the suction pathway within the tube.
Obstruction of a medical tube can impact its effectiveness to remove the fluid and other material for which it was originally placed, eventually rendering the medical tube partially or totally non-functional. In some cases, a non-functional tube can have serious or potentially life-threatening consequences. For example, if there is a blockage in a chest tube following cardiac or pulmonary surgery, the resulting accumulation of fluid around the heart and lungs without adequate drainage can cause serious adverse events such as pericardial tamponade and pneumothorax. In addition to chest tubes used in heart, lung and trauma surgery, other medical tubes are prone to clogging as well, including feeding tubes, surgical wound drains, urinary catheters, cardiovascular catheters and others.
There are few effective techniques to manage medical tube clogging when it occurs. During the perioperative period following chest surgery or trauma, clinicians will undertake measures to try to remove any debris (such as a clot) that has accumulated or formed within the chest tube, to keep the tube clear. One method is to simply tap the tube to try and break up the debris. Another method is referred to as ‘milking the tube.’ ‘Milking’ involves using one's fingers, or a rudimentary device composed of a pair of pliers with rollers fashioned onto its jaws, to compress the tube over the debris to try and break it up. The goal is to loosen the debris, or to break it into smaller pieces, so it can be more readily drawn out of the tube via suction applied at the proximal end.
Another technique is fan folding. In this technique, the clinician bends the chest tube in various ways to try to break up any long clots or other obstructions that extend along the axis of the medical tube. The aim is to produce several smaller pieces of debris, as opposed to one long piece, that will be more readily drawn proximally via the suction applied at the tube's proximal end. Still another technique is known as ‘stripping.’ Here, the clinician takes two fingers lubricated in some fashion, or the improvised device composed of a pair of pliers with rollers mentioned above, and ‘strips’ the tube. This is achieved by compressing the tube initially near where it enters the patient, and drawing the compressing apparatus (one's fingers or other compression device) proximally, with compression still applied, along the tube's length toward the suction source. This is done repeatedly to try and work any obstructive debris out from the tube and toward the suction source.
None of the above techniques is particularly effective. Moreover, they are time consuming and can be quite painful if the patient is awake and alert when they are performed, due to tugging on the medical tube. Tugging on chest tubes whose terminal ends have been placed near the pleura or pericardium can be especially painful. In addition, the ‘stripping’ technique is known to generate short bursts of extreme negative pressure within chest tubes, which in turn draws a strong suction in the body cavity where its terminal end has been placed. This can be quite dangerous in certain circumstances. For example, negative pressures of magnitude greater than −300 cm of water can be generated adjacent suture lines on coronary anastomosis, etc., which can disrupt some of the work that was done during a prior surgery. As a result, many surgeons have banned stripping their patients' chest tubes due to the potential for complications.
When the above techniques fail to clear a potentially dangerous clot within the tube, a more invasive technique must be used. This requires establishment of a sterile field around the chest tube, which is disconnected from the suction source to manually insert a suction catheter to clear the debris. This is known as open chest tube suctioning, and it can be effective to clear a clogged chest tube. But it is highly undesirable for a number of reasons. First, it compromises the sterile field within the chest tube system by exposing the internal environment within that system to the external environment, potentially introducing bacteria inside the chest. Second, the closed system (suction source to chest tube to body space within the chest) typically must be breached to insert the catheter inside the chest tube. Breaking the seal on this system causes loss of the normal physiologic negative pressure inside the chest. This can result in lung collapse (pneumothorax) while suctioning the chest tube. Additionally, the suction catheter can easily be passed beyond the end of the chest tube, which has the potential to injure the heart or lungs, which could be life threatening. Finally, this procedure is time consuming and usually can only be performed by physicians due to the associated dangers. Thus it is only occasionally done in extreme situations when a clogged chest tube is causing a serious acute problem.
Currently, surgeons often implant two or more medical tubes, or employ large-diameter tubes, following surgery to provide additional drainage capacity and avoid potentially life-threatening complications of a clogged tube. Methods and apparatus are desirable to keep medical tubes from clogging or to clear them reliably without having to breach the closed system between the suction source and the body cavity requiring drainage. Such methods/apparatus may allow surgeons to place fewer tubes post-surgery, or to select tubes having smaller diameters, both of which will reduce patient discomfort and recovery time. Placement of fewer tubes also will minimize the risk of infection.